The objective of this project is to investigate the immune functions of burn patients' mononuclear cells. Definition of the cell type(s) and the nature of burn induced immune defects will deliniate possible mechanism(s) by which thermal injury can compromise immunocompetence. The proposal focuses on possible burn-induced aberrations in the interactions of the heterogenous population of monocyte macrophages (M0) and Thymus-derived lymphocytes (T cells). Several different experimental systems are used to examine the effect of burns on M0 cell-T cell activity in immune response induction. The post burn M0 - T cell interactions in T cell proliferation are examined using a T cell mitogen response system. We will investigate the possibility that thermal injury induces increased suppressive or inhibitory M0 and T cells by utilizing a new adaptation of the mixed lymphocyte response (MLR). This same modified MLR system is employed to determine the target cell of burn induced suppressor cells. The effect of thermal injury on M0 cell facilitation of specific immune responses is probed in a system measuring the in vitro generation of specific antibody forming cells (AFC). The inimical effects of burns on M0 function are also examined utilizing assays which measure their production of plasminogen activator (PA), tissue procoagulant factor (TF) and lysozyme. Each of these M0 functions play important roles in the non-specific inflammatory system and may be reflective of M0 ability to interact in the immune system. A new method of inducing human peripheral blood mononuclear cells to produce specific AFC in vitro is described. Combining the information derived from our various experimental systems will furnish a more complete characterization of the burn induced aberrations in M0 and/or T cell function which compromise burn patients' immunocompetence.